3.2.4 properties of period 3 elements and their oxides

Question 1

write a balanced equation for the reaction of sodium with water

Answer 1

2Na(s) + 2H2O — 2NaOH (aq) + H2 (g)

Question 2

state 3 observations from the reaction between sodium and water

Answer 2

fizzing due to H2 produced
sodium floats on water and reacts vigorously forming molten ball
phenolphthalein goes from colourless to pink

Question 3

write a balanced equation for the reaction of magnesium and water

Answer 3

Mg(s) + 2H2O (l) — Mg(OH)2 (s) + H2(g)

Question 4

state an observation for the reaction between water and magnesium

Answer 4

reacts very slowly with cold water so no observable reaction

Question 5

write a balanced equation for the reaction of magnesium and steam

Answer 5

Mg(s) + H2O(g) — MgO(s) + H2(g)

Question 6

state an observation for the reaction between magnesium and steam

Answer 6

white powder
bright white flame

Question 7

write a balanced equation for the reaction between sodium and oxygen

Answer 7

4Na(s) + O2(g) — 2Na2O(s)

Question 8

what is the bonding and structure of the oxide produced between sodium and oxygen?

Answer 8

giant ionic lattice
ionic bonding

Question 9

explain the melting point of sodium oxide

Answer 9

high melting point because it requires lots of energy to overcome the strong electrostatic forces of attraction between oppositely charged ions in a lattice

Question 10

what is an observation from the reaction between sodium and oxygen?

Answer 10

very vigorous reaction, burns with a yellow flame forming sodium oxide which is a white solid

Question 11

write a balanced equation for the reaction between magnesium and oxygen

Answer 11

2Mg(s) + O2(g) — 2MgO(s)

Question 12

what is the structure and bonding of the oxide produced from the reaction between magnesium and oxygen?

Answer 12

giant ionic lattice and ionic bonding

Question 13

explain the melting point of magnesium oxide

Answer 13

high melting point because there is lots of energy required to overcome the strong electrostatic forces of attraction between oppositely charged ions held together in a lattice

Question 14

what can be observed in the reaction between magnesium and oxygen?

Answer 14

very vigorous reaction, burns with a bright white flame forming magnesium oxide which is a white solid

Question 15

write a balanced equation for the reaction between aluminium and oxygen

Answer 15

4Al(s) + 3O2(g) — 2Al2O3 (s)

Question 16

what is the structure and bonding of aluminium oxide?

Answer 16

giant ionic lattice
ionic bonding

Question 17

explain the melting point of aluminium oxide

Answer 17

high melting point so lots of energy required to overcome electrostatic forces of attraction between oppositely charged ions held together in a lattice

Question 18

state an observation from the reaction between aluminium and oxygen

Answer 18

vigorous reaction with a bright white flame forming aluminium oxide which is a white solid

Question 19

write a balanced equation for the reaction between silicon and oxygen

Answer 19

Si(s) + O2(g). — SiO2 (s)

Question 20

what is the structure and bonding in silicon dioxide

Answer 20

macromolecular
covalent bonding

Question 21

explain the melting point of silicon dioxide

Answer 21

high melting point so lots of energy required to overcome many strong covalent bonds

Question 22

state what is observed in the reaction between silicon and oxygen

Answer 22

a slow reaction

Question 23

write a balanced equation for the reaction between phosphorus and oxygen

Answer 23

P4(s) + 5O2 (g) — P4O10 (s)

Question 24

what is the bonding and structure of phosphorus (v) oxide

Answer 24

simple molecular
covalent bonding

Question 25

explain the melting point of phosphorus (v) oxide

Answer 25

low melting point since there are weak van der waals between molecules that are easy to overcome

Question 26

state an observation for the reaction between phosphorus and oxygen

Answer 26

vigorous reaction forming masses of white fumes with a white flame

Question 27

write a balanced equation for the reaction between sulfur and oxygen

Answer 27

s(s) + O2(g) — sO2 (g)

Question 28

what is the structure and bonding of sulphur dioxide?

Answer 28

simple molecular covalent bonding

Question 29

explain the melting point of sulphur dioxide

Answer 29

low melting point because there are weak van der waals between molecules that are easy to overcome

Question 30

state what is observed in the reaction between sulphur and oxygen

Answer 30

melts easily then burns with a blue flame forming sulphur dioxide a colourless gas with a choking smell

Question 31

at high temperature and with a catalyst, SO3 can form from the reaction between sulphur and oxygen, write an equation

Answer 31

S(s) + 1 1/2 O2(g) — SO3(g)

Question 32

what is the PH of the solution formed after sodium and water react?

Answer 32

12-14

Question 33

what is the PH of the solution formed after magnesium and water react?

Answer 33

9-10

Question 34

write a balanced equation to show the reaction between Na2O with water

Answer 34

Na2O(s) + H2O (l) — 2NaOH(aq)

Question 35

what is the PH of the solution formed from the reaction between Na2O and water

Answer 35

12-14

Question 36

write a balanced equation to show the reaction between MgO and water

Answer 36

MgO(s) + H2O(l) — Mg(OH)2 (aq)

Question 37

what is the PH of the solution formed from the reaction between MgO and water

Answer 37

9-10

Question 38

write a balanced equation for the reaction between Al2O3 and water

Answer 38

aluminium is insoluble

Question 39

what is the PH of the solution formed from the reaction between Al2O3 and water

Answer 39

no PH change as its insoluble

Question 40

write a balanced equation for the reaction between P4O10 and water

Answer 40

p4o10(s) + 6H2O(l) — 4H3PO4(aq)

Question 41

what is the PH of the solution formed from the reaction between p4o10 and water

Answer 41

0-1

Question 42

write a balanced equation for the reaction between SO2 and water

Answer 42

silicon is insoluble in water

Question 43

what is the PH of the solution formed from the reaction between SO2 and water

Answer 43

no PH change

Question 44

what is the PH of the solution formed from the reaction between SO2 and water

Answer 44

no PH change

Question 45

write a balanced equation for the reaction between SO3 and water

Answer 45

SO3 + H2O — H2SO4

Question 46

what is the PH of the solution formed from the reaction between SO3 and water

Answer 46

0

Question 47

write an equation for a reaction between Na2O and H2SO4 and a base

Answer 47

acid : Na2O (s) + H2SO4 (aq) — Na2SO4 (aq) + H2O(l) base : not applicable

Question 48

write an equation for the reaction between MgO and HCl and a base

Answer 48

acid : Mgo (s) + 2HCl (aq) — MgCl2 (aq) + H2O (l) base : not applicable

Question 49

write an equation for the reaction between Al2O3 and HCl and NaOH

Answer 49

acid : Al2O3 (s) + 6HCl — 2AlCl3 + 3H2O base : Al2O3 (s) + 2NaOH (aq) + 3H2O — 2NaAl(OH)4 (aq)

Question 50

write an equation for the reaction between p4o10 and NaOH and an acid

Answer 50

acid : no reaction base : p4o10 (s) + 12NaOH (aq) — 4Na3PO4 (aq) + 6H2O (l)

Question 51

write an equation for the reaction between SiO2 and NaOH and an acid

Answer 51

acid : no reaction base : SiO2 (s) + 2NaOH (aq) — Na2SiO3 (aq) + H2O (l)

Question 52

H3PO4 : write three equations, each showing the loss of an acidic hydrogen to form three anions

Answer 52

H3PO4 (aq) — H+ (aq) + H2PO4- (aq) H3PO4 (aq) — 2H+ (aq) + HPO4 2- (aq) H3PO4 (aq) — 3H+ (aq) + PO4 3- (aq)

Question 53

H2SO3 : write two equations each showing the loss of an acidic hydrogen to form two different anions.

Answer 53

H2SO3 (aq) — H+ (aq) + HSO3- (aq) H2SO3 (aq) — 2H+ (aq) + SO3 2- (aq)

Question 54

H2SO4 : write two equations each showing the loss of an acidic hydrogen to form two different anions.

Answer 54

H2SO4 (aq) — H+ (aq) + HSO4 - (aq) H2SO4 (aq) — 2H+ (aq) + SO4 2- (aq)

Question 55

what is the shape of H3PO4?

Answer 55

tetrahedral

Question 56

what is the shape of H2SO3?

Answer 56

trigonal pyramidal

Question 57

what is the shape of H2SO4?

Answer 57

tetrahedral

Question 58

predict whether the melting point of lithium oxide is higher than, the same as, or lower than the melting point of sodium oxide and explain your prediction

Answer 58

higher because the Li+ ion is smaller than the Na+ ion so attracts O2- more strongly

Question 59

in K, what is the avg. melting point of Na2O?

Answer 59

1548

Question 60

in K, what is the avg. melting point of MgO?

Answer 60

3125

Question 61

in K, what is the avg. melting point of Al2O3?

Answer 61

2345

Question 62

in K, what is the avg. melting point of SiO2?

Answer 62

1883

Question 63

in K, what is the avg. melting point of p4o10?

Answer 63

573

Question 64

in K, what is the avg. melting point of SO2?

Answer 64

200

Question 65

in K, what is the avg. melting point of SO3?

Answer 65

290

Question 66

explain why sodium oxide forms an alkaline solution when it reacts in water

Answer 66

sodium oxide contains O2- ions which react with H2O to form OH- ions

Question 67

write an ionic equation for the reaction of phosphorus oxide with an excess of sodium hydroxide solution

Answer 67

P4O10 + 12OH- — 4PO4 3- + 6H2O

Question 68

why is phosphorus stored under water?

Answer 68

to prevent it from reacting with oxygen

Question 69

how could you distinguish between the colourless gases of SO2 and SO3?

Answer 69

dissolve in separate samples of water and test PH, more acidic solution is SO3

Question 70

predict whether the melting point of lithium oxide is higher than, the same as, or lower than the melting point of sodium oxide and explain your prediction

Answer 70

higher Li+ ion is smaller than Na+ ion so attracts O2- more strongly

Question 71

explain why magnesium has a higher melting point than sodium

Answer 71

Mg+ has a higher charge than Na+ so attracts delocalised electrons more strongly

Question 72

other than a high melting point, give two physical properties of silicon dioxide that are characteristic of its structure and bonding

Answer 72

hard insoluble

Question 73

phosphorus (v) oxide is known as pentoxide suggest why it is usually represented by p4o10 rather than p2o5

Answer 73

one molecule contains 4 P and 10 O

Question 74

explain why an excess of magnesium oxide can be used for neutralisation

Answer 74

MgO is sparingly soluble

Question 75

explain why the use of excess sodium hydroxide to neutralise phosphoric acid solution might lead to environmental problems

Answer 75

excess of sodium hydroxide would make the lake toxic

Question 76

suggest why sulfur dioxide forms a weakly acidic solution

Answer 76

reaction is an equilibrium

Question 77

suggest why silicon dioxide is described as an acidic oxide even though it is insoluble in water

Answer 77

SiO2 reacts with bases

Question 78

explain why the melting point of magnesium is higher than that of sodium

Answer 78

magnesium has a higher nuclear charge than sodium it is a smaller atom meaning there is a strong attraction between the ions and delocalised electrons

Question 79

explain how metals conduct electricity

Answer 79

through a sea of delocalised electrons that flow in a given direction

Question 80

state and explain the trend in the melting points of the period 3 metals Na, Mg and Al

Answer 80

increases nuclear charge increases stronger attraction between cations and delocalised electrons

Question 81

in terms of atomic structure, explain why the van der waals forces in liquid argon are very weak

Answer 81

argon particles are single atoms with electrons closer to the nucleus so cannot be easily polarised

Question 82

explain why the second ionisation energy of sodium is greater than the second ionisation energy of magnesium

Answer 82

Na2+ requires loss of electron from 2p orbital

Question 83

state why more than minimum energy is not used to ionise the sample of indium

Answer 83

so more than one electron is knocked out

Question 84

explain why nickel is ductile

Answer 84

layers of ions can slide over one another

Question 85

state one reason why the first ionisation energy of rubidium is lower than the first ionisation energy of sodium

Answer 85

rubidium is a bigger atom

Question 86

state one reason why the first ionisation energy of rubidium is lower than the first ionisation energy of sodium

Answer 86

rubidium is a bigger atom